By late morning, 60 percent of the power had been restored in the eight northern states affected by the outage and the rest was expected to be back on line by the afternoon, Shinde said. The grid was drawing power from the neighboring eastern and western grids as well as getting hydroelectric power from the small neighboring mountain kingdom of Bhutan.

New Delhi residents were roused from sleep when their fans and air conditioners stopped and came out of their homes in the heat as the entire city turned dark. Temperatures in the city were in the mid-30s (90s Fahrenheit) with 89 percent humidity. New Delhi's Metro transit system, with 1.8 million daily riders, stopped for hours during the morning commute. Some trains across the northern region were stranded when their electric engines failed. Others were delayed by hours as they were hooked to diesel engines.

While the outage was unique in its reach, its impact was softened by Indians' familiarity with almost daily power outages of varying duration.